Liquid fuel supply system



P 1950 R. J. IFIELD 2,523,214

LIQUID FUEL SUPPLY SYSTEM Filed Feb. 26. 1947 0 s g s a in,

t z 41 b 0 02 5 o in h "k IV T Patented Sept. 19, 1950 LIQUID FUEL SUPPLY SYSTEM Richard Joseph Ifield, Birmingham, England, as-

signor to Joseph Lucas Limited, Birmingham,

England Application February 26, 1947, Serial No. 731,159 In Great Britain February 4, 1946 Section 1, Public Law 690, August a, 1946 Patent expires February 4, 1966 1 Claim.

This invention relates to. liquid fuel supply systems of the kind used in conjunction with the combustion chambers of internal combustion prime movers, furnaces and the like, and in.

which the liquid fuel before discharge through a nozzle is caused to pass through'a swirl chamber wherein rotary motion is imparted to the liquid.

To maintain an adequate rate of rotation over a wide range of variation of the rate of discharge, it is already known to supply excess liquid to the nozzle, and return the excess from the swirl chamber to the system along a pipe which forms with the main part of the system a localised path in which the excess liquid can be circulated. The object of the present invention is to enable the desired regulation of such a system to be effected in a convenient and satisfactory manner.

The invention comprises a system as aforesaid having in combination, a main variable delivery pump, a secondary pump in the circulatory part of the system by which excess liquid is returned from the nozzle or' nozzles, means for establishing a pressure difierence in the said part of the system, and means responsive to the pressure difference for automatically regulating the output of the main pump.

The accompanying drawing illustrates diagrammatically one embodiment of the invention.

Referring to the drawing, I employ a main variable delivery pump a which in the example illustrated is of the well known swash-plate type. The illustrated form of the main pump will be described hereinafter. It is sufiicient at this stage to say that the main pump a is provided with an output-regulating member t, and with a driving shaft a adapted to receive motion from the prime mover (not shown) to be supplied with liquid fuel by the main pump. Liquid fuel is supplied to the main pump a from a storage tank by a pipe b. The fuel is delivered from the pump to a discharge nozzle (or nozzles) c by a pipe d. Between the swirl chamber e of the nozzle or each nozzle and a point 1 in the pipe at at the delivery side of the main pump a I connect return pipes g which together with the portion of the pipe between the point I and the nozzle or nozzles form a circulatory path for the excess liquid fuel required to be supplied to the swirl chamber or chambers for maintaining an adequate rotary motion of the liquid fuel in the swirl chamber or chambers over a. wide range of variation in the rate of discharge of liquid fuel from the nozzle or nozzles. In this circulatory path I arrange a secondary pump h for efary pump will be described hereinafter.

fecting therequired flow of liquid fuel through the circulatory path. In the form illustrated the secondary pump it is of the well known swashplate type. The illustrated form of the second- It is suflicient at this stage to say that the secondary pump h is provided with a manually operable output-regulating member t and with a driving shaft h adapted to receive motion from the prime mover.

Also between the pump it and the junction f with the pipe d, I provide in the said path a restricted orifice 1' adapted to set up a convenient pressure difference between the two sides of the orifice. Further the two sides of the orifice are connected by pipes or passages 7, Into any con-, venient means responsive to the pressure difference, for causing aetuation'of the output-regulating member t of the main pump a. For example I may employ a bi-compartmental chamber m containing a spring loaded diaphragm n which is adapted to actuate a. valve 0 for controlling a pressure fluid whereby the outputregulating member t of the main pump a is actuated in the manner hereinafter described, the compartments at the opposite sides of the diaphragm being connected by the passages k to the opposite sides of the restricted orifice 2'.

When the secondary pump it is in action with its output-regulating member I. in any given position, the pressure difference across the restricted orifice i varies with the speed of the secondary pump. When the output-regulating member t of the main pump a is in its maximum delivery position, the amount of liquid fuel supplied by the main pump to the nozzle or nozzles c is sufiiciently large to effect the required rotary motion of the fuel in the swirl chamber e of the nozzle or each nozzle 0. In this condition the output-regulating member t of the secondary pump it is manually adjusted to reduce the output of this pump, and until the speed of the secondary pump is increased sufliciently to create a predetermined pressure difference across the restricted orifice i, the output-regulating member 1! of the main pump a will remain in its maximum delivery position. When, however, this predetermined pressure difference across the orifice i is reached, the consequential movement of the diaphragm 11. opens the valve 0, and thereby causes the output-regulating member t of the main pump a to reduce the output of this pump in the manner hereinafter described. Conversely, when less fuel is required from the main pump a, the output-regulating member t of the acaaaie secondary pump h is manually adjusted to increase the output of the secondary pump, so that, the predetermined pressure diiference across the orifice i is produced at a lower speed of the secondary pump. This reduces the speed of the main pump, and consequently the amount of fuel supplied by this pump to the nozzle or each nozzle 0. However. the increased amount of fuel circulated by the secondary pump h ensures. that the amount of fuel flowing through the swirl chamber e of the nozzle or each nozzle is sumcient to efiect the required rotary motion of the fuel in the swirl chamber.

Whilst any convenient main and secondary pumps may be used in the system above de-' scribed, the forms of pump illustrated are as previously indicated of the well known'swashplate type. The main pump a comprises a hollow body part in which is arranged a rotary part r to which motion can be imparted by the driving shaft a The rotary part r is formed with bores containing reciprocatory spring loaded plungers s the outer ends of which co-operate with an angularly adjustable swash plate forming the output-regulating member t. The output of the pump is varied by adjustment of the swash plate, and this effected by a, piston p con-' nected to the swash plate and loaded by a spring w. Pressure fluid is supplied from the main pump a to both ends of a chamber 1 containing the piston p, the said ends being connected to the outlet 2 of the main pump by passages 2 one of which is formed with a, restriction :c. The end of the chamber 3 containing the spring w is connected by a pipe or passage 3 with the valve 0. When this valve is opened the said end of the chamber is put into communication with a sump or the supply side of the main pump, and the pressure of the fluid in the other end of the said chamber can then move the piston in the direction for reducing the pump output. Conversely when the valve 0 is closed the spring w moves the-piston p in the opposite direction for increasing the output of the main pump a.

The secondary pump it shown in the diagram is similar to the main pump a. excepting that angular adjustment of the swash plate is effected by a hand lever '11. In other respects parts of the secondary pump h similar to parts of the main pump a are indicated by the same reference characters sufllxed by 2. a

Having thus described my invention what I claim as new and desire ,to secure by Letters Patent is:

In a liquid fuel supply system of the kind specified, the combination of a main variable delivery' pump, at least one discharge nozzle havin associated with it a swirl chamber through which the nozzle can be supplied with liquid fuel from the pump, and to which the pump can sup- -ply liquid fuel in excess of the quantity required to be discharged by the nozzle, means connected to the main pump and the nozzle and forming a path through which the excess fuel from the swirl chamber can be circulated, a secondary pump in the said path for circulating the excess fuel therethrough, flow-restricting means in the said path for establishing a pressure difference therein, and means responsive to the said pressure difference for automatically regulating the output of the main pum-p.

RICHARD JOSEPH IFIELD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,658,307 Small Feb. 7, 1928 1,877,091 Vickers Sept. 13, 1932 1,970,380 Hosel Aug. 14, 1934 2,069,327 Ray et a1 Feb. 2, 1937 2,366,388 Crosby Jan. 2, 1945 

